vault backup: 2025-01-13 13:16:06

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+#openstack #nova #live-migration #volume
+
+
+---
+Table cinder.volume_attachment, contains which volume_driver. target_lun `(<n>)` here maps to `dm-<n>`.
+Luns are not unique across pod, each node has a target_lun 2 and thus dm-2 connected.
+
+os-brick is responsible for connecting volumes;
+if connection_info it receives contains target_iqns, target_luns etc it will not do a scan and just returns those. 
+`@see os_brick/initiator/connectors/iscsi.py`
+
+`nova/virt/libvirt/driver.py -> def _connect_volume` does attaching of volumes using os-brick. Driver exposes some methods that do this and are called elsewhere: `swap_volume`, `attach_volume`, `pre_live_migration`. 
+
+`pre_live_migration` is called by `nova/compute/manager.py`
+
+So in `nova/compute/manager.py` there is a function that does the rollback, and it rollbacks bdm's and deletes volume attachments before it calls `rollback_live_migration_at_destination` which in turn makes an attempt at deleting the actual volume attachment to the node. But at that point all objects have been rollbacked already so it has invalid information.
+
+If the code in new versions of openstack isn't any different i'll just make a bug report and see what they come up with.